The present invention relates to an internal combustion engine that operates on a stratified fuel charge.
Air pollution from auto exhaust gas is a serious public nuisance. Just how to completely eliminate the harmful components of the exhaust gas is a perplexing problem, and while various solutions have been proposed, none have operated in an efficient and trouble-free manner.
The present invention aims at solving this problem by stratifying the burning state of the mixed gas in the engine cylinder.
It is well known that whereas the theoretical mix ratio, i.e., air-fuel ratio (weight ratio) in a gasoline-burning engine should usually be around 14.7:1, the existing auto engines are on the average run at an extremely high mix ratio, that is, at a high output ratio of 10-12:1 under non-steady state of starting or acceleration and at a ratio of 13-16:1 under steady state of constant speed operation. It is equally well known that if the mixed gas is to be completely burned for removal of its harmful components, the gas must have at least 10-20% more air than at the theoretical mix ratio. However, at such low mix ratios the output of the engine is too low to meet practical standards of use.
Thus, the so-called stratified combustion method was proposed in which a rich mixed gas is locally concentrated around the spark plug by various means to thereby increase the ignitability and the burning rate. A lean mixed gas with ample excess of air is supplied to the other parts of the cylinder so that complete combustion takes place with the burning flame of the rich mixed gas. This method has so far failed to find wide application because of difficulties in adjusting the two systems of rich and lean mixed gases.
Lately, to overcome these difficulties a Soviet torch type engine was proposed in which a carburetor for generating the two systems of rich and lean mixed gases and two suction valves within a single cylinder are provided. One of the valves opens into the pre-combustion chamber for filling the chamber with a rich mixed gas for complete combustion but the overall system is fatally defective in that its mechanism is complicated and the ventilation of the pre-combustion chamber is insufficient.